The present invention relates to a spray head for a dispenser for dispensing a fluid, and more particularly to a spray head provided with a closure member.
Closure members for closing the outlet orifice of a spray head are, in particular, used in the pharmaceuticals field for solving the problem that at least some of the fluid that is to be dispensed risks becoming contaminated. Such closure members are generally actuated, i.e. opened, by the pressure generated by the pump while it is being actuated.
A commonly-used type of closure member is made in the form of a one-way valve, and it comprises a piston that can be slid and moved by the pressure generated by the pump. In general, the piston is mounted inside the expulsion channel via which the fluid is expelled from the dispenser device. The expulsion channel must therefore be large enough to contain the piston and to enable said piston to move. Such closure members are described in particular in Documents FR-2 671 329, and U.S. Pat. No. 4,830,284.
A drawback with those devices it that they do not make it possible to minimize unused volume. An essential characteristic of most current spray devices is that unused volume-in the expulsion channel is minimized. Such minimization is particularly important when the pumps need to be primed, where priming consists in actuating them one or more times to expel the air from the pump chamber and to replace it with the liquid to be dispensed. In order to open the dispensing orifice, and therefore in order to displace the closure member that closes it, it is necessary to generate sufficient pressure by actuating the pump. In which case, the larger the volume, i.e. the larger the quantity of air, the higher the number of times the pump must be actuated in order to prime it. In some cases, priming even becomes impossible, and standard-type pumps are not suitable for that type of application.
One way of solving that problem is to organize the closure member in a manner such that the fluid expulsion channel is defined inside the moving closure member which is then mounted to move relative to a fixed element of the spray head. In which case, the closure member incorporates the outlet orifice, and the expulsion channel is defined between said closure member and said fixed element of the spray head, which fixed element can then be organized in a manner such that the unused volume in the expulsion channel is minimized. Such a device is described, in particular, in Document DE-435 138.
Unfortunately, that type of device suffers from another major drawback. An essential requirement for spray devices nowadays is that the generated spray must be of good quality and must be constant every time the device is actuated. To produce such spray characteristics, spray heads generally include spray portions that are connected to the spray orifices and that are of particularly critical geometrical configuration. Such a spray portion is commonly made up of very narrow channels disposed at different angles and connected to the spray orifice. In the above-described known devices, it is clear that the geometrical configuration of the spray portion is modified considerably by the presence of closure members. The same applies to deformable closure members which, instead of being displaced in the expulsion channels, have deformable closure portions that open under the pressure of the fluid.
Document U.S. Pat. No. 3,913,803 discloses a closure member which is mounted to slide around a fixed element of the spray head, and which is organized in a manner such that, when it is in the spray position, a swirl chamber is generated upstream from the spray orifice as well as swirl channels connected to said swirl chamber so as to generate a proper spray. That swirl geometrical configuration is achieved by means of ribs and corresponding grooves, respectively on the moving closure member, and in the fixed element of the spray head.
Although that document makes it possible to generate a spray on actuating the device, the quality of the spray remains insufficient. The spray geometrical configuration as a whole, i.e. the swirl channels and the swirl chamber, is influenced by the closure member being displaced from its closed position to its spray position. In particular, the closure member being displaced gives rise to a progressive increase in the size of the geometrical configuration of the spray, which adversely affects the quality of the spray, in particular the constancy thereof each successive time the device is actuated. In that case, the quality and the intensity of the spray are dependent on the actuating force exerted on the pump, and actuating the pump too weakly can generate a poor quality spray.
Documents U.S. Pat. Nos. 4,120,456, 4,182,496, and EP-0 686 433 disclose closure members mounted to slide in dispenser heads so as to open and close the dispensing orifice. Such a head incorporates the orifice and the swirl profile, and the closure member is displaced towards the inside of the head away form the orifice by the pressure of the fluid. That type of closure member suffers from several drawbacks. Firstly the co-operation between the closure member, the dispenser orifice, and the spray profile must be defined very accurately so as to avoid both leakage and also any risk of the closure member jamming. Therefore, no dimensional tolerance is allowed, which complicates manufacture and assembly of the device. Secondly, in order to enable the closure member to be displaced towards the inside of the head, said head must be quite large in size, and the problem arises of too large an unused volume in the rest position. In addition, the efficiency of the device is not good because, in order to open the closure member, the pressure of the fluid acts in the opposite direction to the direction in which the fluid is expelled.
Another problem that can arise with spray heads concerns the risk of the fluid being contaminated at the spray orifice and/or at the closure member. With certain types of closure members in which the closure member slides relative to the spray head, there is a narrow gap between the closure member and the head, and bacteria or germs can penetrate into the head via said gap.
An object of the present invention is to provide a spray head for a fluid dispenser, which spray head does not reproduce the above-mentioned drawbacks.
An object of the present invention is thus to provide a spray head including a closure member, in which spray head the quality of the spray that is generated is good and constant each time the device is actuated. In particular, an object of the present invention is to provide a spray head in which the quality of the generated spray is identical to the spray from a device that does not have a closure member for closing the spray orifice.
An object of the present invention is also to provide a spray head provided with a closure member and in which the unused volume of the expulsion channel is minimized.
Another object of the present invention is to provide such a spray head that is simple and low-cost to make and assemble.
An object of the present invention is also to provide such a spray head that prevents any contamination of the fluid at the closure member and/or at the spray orifice.
Another object of the invention is to provide such a spray head that achieves all of the above-mentioned objects.
The present invention thus provides a spray head for a fluid dispenser for dispensing a fluid, the spray head being provided with an expulsion channel opening out in a spray orifice, and with a moving closure member mounted to move between a closed position, in which it closes said orifice, and a spray position, said closure member being urged resiliently towards its closed position, and being displaced towards its spray position by the pressure of the fluid, the spray head further being provided with a swirl chamber of variable volume, the volume of said swirl chamber being at its maximum when the closure member is in the spray position, and being substantially zero when said closure member is in the closed position, and said closure member is provided with the spray orifice and with swirl channels which, when the closure member is in the spray position, connect said expulsion channel to said swirl chamber, the volume and the geometrical configuration of said channels remaining unchanged whatever the position of the closure member.
Preferably, one end of the moving closure member is provided with the spray orifice and its other end is provided with a piston mounted to slide in leaktight manner in the expulsion channel.
Advantageously, in the closed position, the spray orifice is closed by an insert disposed in fixed manner in the expulsion channel, said swirl chamber being formed between said insert and said spray orifice when the closure member moves towards its spray position.
Preferably, said swirl chamber is cylindrical, the side wall and the top end face being formed by the closure member, and the bottom end face being formed by the insert.
Advantageously, said swirl channels open out in said side wall of the swirl chamber so that, when the closure member is in the closed position, they are closed by said insert.
Advantageously, said moving closure member comprises a hollow tubular sleeve provided with an end wall incorporating the spray orifice at its center, and a short hollow tube fitted in fixed manner inside the tubular sleeve in abutment against said end wall, the top surface of said tube that is in abutment against the end wall of the closure member being provided with one or more spray channels connecting the outside peripheral surface of said tube to the inside peripheral surface of said tube.
Advantageously, said short hollow tube is provided with one or more passageways in its outside peripheral surface fitted into the tubular sleeve of the closure member, said passageways being connected to said channels and forming a portion of the expulsion channel.
Preferably, said closure member is disposed to slide around an insert disposed in fixed manner in the spray head, said expulsion channel being defined at least in part between said closure member and said insert.
In an advantageous embodiment, said spray head comprises a body, a gasket-forming resilient element being disposed between the moving closure member and the body of the spray head, said resilient member urging said closure member towards its closed position and being compressed when the closure member moves towards its spray position.
In another advantageous embodiment, said spray head comprises a body underlying an elastically-deformable element fixed to said body, the closure member co-operating with said element which urges said closure member towards its closed position, and which is deformed when the closure member moves towards its spray position.
Preferably, the resiliently-deformable element is fixed in leaktight manner to said body of the spray head, and to said closure member, so that the leaktightness is guaranteed when the closure member is in any of its positions.
Advantageously, said elastically-deformable element is a cap made of elastomer thermoplastic.
Advantageously, one or more portions of said spray head that are in contact with the fluid include a bacteriostatic material.